Getting Your Green Manure/Cover Crop Established

Planting green manure/cover crops – either during fallow periods or in season between the rows of widely spaced vegetable crops like pumpkins is a sound agronomic practice. The cover/green manure crops suppress weeds, protect against soil erosion, scavenge nutrients from deep in the soil profile and contribute valuable organic matter to the soil. Getting quick emergence of a uniform thick stand is critical to achieving an effective cover crop. While drilling in the seed is the standard approach to establishing field crops – many growers of vegetable crops do not own seed drills. Standard size drills are also too large to be used to seed between the rows in widely spaced vegetable crops. Broadcasting and then incorporating the seed of the cover crop via shallow tillage represents a practical option for most growers. However, the degree of success achieved with broadcast/incorporating varies with the crop, the method of tillage, seedbed conditions and weather after seeding. Brennan and Leap (2014) recently compared stand establishment in a rye/vetch cover crop seeded either by drilling or by broadcasting then incorporation the seed via rotovating, cultivating or using a tandem disc. Drilling consistently gave the fastest emerging, thickest stand – but using a rotovator set to till to a depth of 10cm to incorporate the broadcast seed also produced a very good stand. The slow/uneven emergence of the broadcast crop incorporated by cultivation or discing was attributed to excessively deep burial of some of the seed. The vetch was more sensitive to excessively deep burial than the rye. While a higher seeding rate could at least partially offset the reduced stand achieved with broadcast/incorporation of the seed, Brennan and Leap point out that the added seed cost coupled with the added equipment and labor costs associated with the 2 step process of broadcasting then incorporating the seed would likely soon exceed the cost of purchasing a suitable drill seeder.